Genetic differences in the histochemically defined structure of oligosaccharides in mice

A wide range of tissues from three interfertile species of mice and an interspecific hybrid was examined with lectins conjugated to peroxidase to localize specifically glycoconjugates containing terminal alpha-N-acetylgalactosamine, alpha-galactose, and alpha-fucose, and the terminal disaccharide galactose-(beta 1----3)-N-acetylgalactosamine. This battery of lectins disclosed marked heterogeneity of glycoconjugates in different histological sites in a given animal and even between cells in a presumably homogeneous cell population within an organ. No variation with any lectin was observed between individuals of two closely related inbred strains of Mus domesticus at any specific histological or cytological site. In contrast, littermates of an outbred strain of Mus castaneus differed in binding of certain lectins at various sites, attesting to a genetic basis for individual variation. Hybrids between castaneus and domesticus mice also showed individual variation. Moreover, extensive differences between the mouse species were demonstrable with every lectin in glycoconjugates of stored secretions, Golgi cisternae, and apical or basolateral plasmalemma in many cell types. Totaling the differences in tabulated staining intensities for each possible species pair gave a measure of the overall extent of difference at 53 histological sites. According to this measure, the three species are about equally divergent from one another. Some differences between species appeared to depend on histological rather than histochemical variation, as, for example, a greater abundance of granular duct cells in the sublingual and submandibular glands in Mus hortulanus. Other differences were apparently derived from pathological change, as exemplified by casts and lymphoid infiltrates in kidney and structurally atypical submandibular gland lobules in Mus castaneus, and possibly by infiltrating cells in intestinal lamina propria and epithelium in Mus castaneus and hortulanus.     

Region-specific ontogeny of alpha-2,6-sialyltransferase during normal and cortisone-induced maturation in mouse intestine

Regional differences in the ontogeny of mouse intestinal alpha-2,6-sialyltransferase activities (alpha-2,6-ST) and the influence of cortisone acetate (CA) on this expression were determined. High ST activity and alpha-2,6-ST mRNA levels were detected in immature small and large intestine, with activity increasing distally from the duodenum. As the mice matured, ST activity (predominantly alpha-2,6-ST) in the small intestine decreased rapidly to adult levels by the fourth postnatal week. CA precociously accelerated this region-specific ontogenic decline. A similar decline of ST mRNA levels reflected ST activity in the small, but not the large, intestine. Small intestinal sialyl alpha-2,6-linked glycoconjugates displayed similar developmental and CA induced-precocious declines when probed using Sambucus nigra agglutinin (SNA) lectin. SNA labeling demonstrated age-dependent diminished sialyl alpha2,6 glycoconjugate expression in goblet cells in the small (but not large) intestine, but no such regional specificity was apparent in microvillus membrane. This suggests differential regulation of sialyl alpha-2,6 glycoconjugates in absorptive vs. globlet cells. These age-dependent and region-specific differences in sialyl alpha-2,6 glycoconjugates may be mediated in part by altered alpha-2,6-ST gene expression regulated by trophic factors such as glucocorticoids.     

Lectin histochemistry of goblet cell sugar residues in the gut of the chick embryo and of the newborn.

The anlage of duodenum, ileum and colon were removed from chick embryos of day 8-21 of incubation and from 1-day-old chicks. A battery of seven different horseradish peroxidase-conjugated lectins (PNA, SBA, DBA, Con A, WGA, LTA and UEAI) was used to study the carbohydrate residues of the glycoconjugates in the goblet cells of the three parts of the intestine. The main results can be summarized as follows: differences in lectin binding were absent in the proximal and distal parts of the duodenum, ileum and colon. Lectin histochemistry showed differences among the three intestinal segments for the time of appearance of the oligosaccharides in the goblet mucus. In the colonic goblet cells of 1-day-old chicks, LTA and UEAI lectins showed two different types of linkage of alpha-L-fucose. This is the first demonstration of UEAI reactive sites in Gallus domesticus.     

Lectin-defined cell surface glycoconjugates of pancreatic cancer cells and their nonmalignant counterparts

Alterations of cell surface carbohydrates of human pancreatic cancer cells from long-term cultures (COLO 357, RPMI 7451, PC 103, PC 107) were assessed ultrastructurally by use of an array of lectin-enzyme conjugates, and compared with lectin-defined changes of glycoconjugates on human pancreatic tissue sections of normal and various pathological conditions. Ulex europeus and, to a lesser degree, Lotus tetragonolobus lectin binding indicate that L-fucose-containing glycoconjugates are expressed predominantly on pancreatic cancer cell surfaces, but not, or restricted to intracytoplasmic structures, on nonmalignant pancreas cells. A comparable binding pattern to pancreatic carcinoma cells is found for Phaseolus vulgaris lectin. This is in contrast to the results with soy bean lectin, the reactivity of which was not restricted to cancer cell surfaces, and with Helix pomatia lectin, which did not bind to pancreatic cancer cells at all, although the latter three lectins possess similar sugar specificities. Between the long-term-cultured malignant pancreas cells differences were observed concerning the binding of wheat germ and pokeweed lectin. Besides, qualitative assets of lectin-binding absorption analyses elaborated quantitative differences in the expression of lectin-defined glycoconjugates on pancreatic cancer cell surfaces.     

Histochemistry of glycoconjugates in mucous cells of Salmo trutta uninfected and naturally parasitized with intestinal helminths

Mucus secreted onto the surface of the intestine forms a physical barrier to invading parasites so that a possible attachment of helminths to the surface is prevented and their expulsion by peristalsis facilitated. In mammals, intestinal parasites induce hyperplasia and hypertrophy of intestine goblet cells and provoke changes in the mucus composition. In fish, this topic has received less attention. In the present investigation, histochemical methods were employed to compose intestinal mucous cell numbers and their glycoconjugate composition were compared by uninfected brown trout Salmo trutta and in S. trutta parasitized with Cyathocephalus truncatus or Pomphorhynchus laevis. When P. laevis was present in the intestine of the brown trout, the total mucous cell number, and the number of mucous cells containing acid or mixed glycoconjugates were significantly enhanced. No significant change in the total mucous cell number was detected in the intestine of fish parasitized with C. truncatus in comparison with uninfected brown trout. A significant increase was observed in the number of both acid (especially sulphated) and mixed glycoconjugates containing mucous cells as well as a significant decrease in the number of neutral glycoconjugates containing mucous cells. When intestinal helminths were present, the thickness of the adherent mucous gel increased. In a limited number of other fish species, the occurrence of gill and intestinal parasites has been reported to increase the mucosal glycoconjugate secretions. Our study is the first quantitative report on the effects of intestinal helminths on the density of mucous cells and mucus composition in a fish species.     

Histomorphological and histochemical characteristics of the intestine of the Senegal sole, Solea senegalensis.

The Senegal sole, Solea senegalensis has been exploited extensively in aquaculture from different countries; at present an intensive production of larvae and adults is being achieved with some nutritional problems. Since this species displays very different life styles and feeding habits at different stages of its life history (larvae, metamorphosis, adults), and because digestive mucins are implicated in different physiological processes including: increase of digestive efficiency, promotion of macromolecules-absorption, buffering of intestinal fluid, prevention of proteolytic damage to the epithelium and defence against bacteria, etc., we studied the histomorphological aspects, as well as the histochemical distribution of carbohydrates, (PAS, Alcian Blue), proteins (Bromophenol Blue), lipids (Oil Red O, Black Sudan B) and glycoproteins (Horseradish peroxidase-conjugated lectins) in the intestinal epithelium of adult Solea senegalensis specimens. Our data are compared with those obtained in larvae and adults of this and other fish species. Primary and secondary folds, microvilli of the intestinal enterocytes, as well as mucous or goblet cells were observed with a scanning electron microscope. Enterocytes and mucocytes of the intestine of adult Solea senegalensis were characterized by a rich supply of sugar and oligosaccharides. Carbohydrates (glycogen and mucins), proteins and lipids were present in cytoplasm and microvilli--brush border--of the enterocytes, which contain GalNAc, GlcNAc, Man, Glc and sialic acid-N-acetyl-D-galactosamine glycoconjugates. Intestinal mucous cells were strongly or weakly stained with Alcian Blue (pH 2.5 and 1). PAS reactivity was intense in numerous goblet cells, but some cells were PAS unreactive or weakly stained. Some goblet cells were positive for Bromophenol Blue but numerous cells were unstained; thus many proteins and possibly lipids may be conjugated with sugars. A similar reactivity to WGA and to neuraminidase-WGA was identified in some intestinal goblet, which were Con A unreactive, indicating the absence of Man and/or Glc and NANA glycoconjugates. GalNAc residues were only scarcely present in glycoproteins of some goblet cells.     

Morphological and histochemical peculiarities of the gut in the white sturgeon, Acipenser transmontanus.

The gut of adult sturgeon was examined. The oesophageal mucosa contained numerous caliciform cells, synthesizing both neutral and acidic glycoconjugates, the latter of the sialylated type. The deep tunica propria-submucosa contained lobules of multilocular adipose tissue, specially abundant during the cold season. The oesophageal tunica muscularis was made up of a large sheath of striated muscle fibres, arranged orthogonally to a thin, subserous smooth muscle layer. The siphon-shaped stomach showed a ciliated epithelium in cardiac and gastric proper gland zones, where tubular glands were present in the tunica propria. The columnar cells which composed the superficial epithelium and gastric pits were demonstrated to synthesize almost exclusively neutral glycoconjugates. Appendices pyloricae constituted a glandular body equipped with intestinal mucosa. The intestinal mucosa was organized in folds, containing numerous caliciform cells which synthesized neutral or acidic glycoconjugates, the latter either of the sialylated and sulphated type. The sulphoglycoconjugates were more abundant in the caliciform cells of the distal intestinal tracts. The tunica propria-submucosa of the spiral valve (medium intestine) contained lymphatic tissue and large lymphatic follicles. A muscularis mucosae was present only in the rectum, where in addition a peculiar granular cell type was present in the superficial tunica propria-submucosa, possibly related to defensive properties. The subserous connective tissue contained pancreatic lobules all along the stomach and intestine. The enteric nervous system showed some special aspects, the most intriguing of which was the presence of large, longitudinally oriented nerve bundles in the t. propria-submucosa of oesophagus and cardiac stomach. The nerve bundles contained, near unmyelinated nerves, some myelinated nerves, as well as neuronal bodies. Both these aspects are exceptional in vertebrates and obscure in their significance. The structural and histochemical aspects we here describe are in part different from those described for other fish. Some of these special features are possibly related with special functional roles, others require a deeper insight and different approaches to clarify them functionally.     

The DHE cell line as a model for studying rat gastro-intestinal mucin expression: effects of dexamethasone

The expression of mucin genes was evaluated in rat intestinal cell lines in order to establish an in vitro model for investigating the regulation of intestinal mucin expression in this species. Two rat intestinal cancer cell lines (DHE, LGA) and three nontumoral rat intestinal cell lines (IEC6, IEC17, IEC18) were screened. The mRNA expression of rMuc1, rMuc2, rMuc3, rMuc4, and rMuc5AC mucin genes was studied by semiquantitative RT-PCR, real-time RT-PCR and Northern-blot analysis. Results were correlated with immunohistochemical expression of rat gastric and intestinal mucin proteins, and secretion of glycoconjugates was examined by enzyme-linked lectin assay. We showed that mRNA of rMucl and rMuc2 were constitutively expressed in all IEC cell populations but periodic acid Schiff staining of these cells did not reveal the presence of glycoproteins. DHE cells expressed rMuc1-5AC mRNA and LGA expressed the same mucins but the level of rMuc4 was much lower. Mucin mRNA expression also differed in relation with the length of cultivation. Immunocytochemical studies revealed the presence of gastric and intestinal mucins in the two tumoral cell lines. Functional experiments showed that bethanechol, A23187 and PMA stimulated release of glycoconjugates in DHE but not in LGA cells. Treatment of DHE cells with dexamethasone (10(-7) mol/l) enhanced rMuc2 mRNA but decreased rMuc1 and rMuc5AC mRNA. Real-time RT-PCR showed that the expression of rMuc1 and rMuc5AC genes was reduced by more than tenfold after 24 h. The increased expression of rMuc2 gene was confirmed by Northern blot analysis. In conclusion, DHE cells provide a valuable cellular model for research on rat mucin secretion and expression.     

Cationic colloidal gold — a probe for light- and electron-microscopic characterization of acidic glycoconjugates using poly-l -lysine gold complex

Summary Cationic colloidal gold (CCG) was used to characterize acidic glycoconjugates in semithin and ultrathin sections of rat large intestine and salivary glands embedded in hydrophilic Lowicryl K4M resin. It was prepared from poly-l-lysine and 10 nm colloidal gold solution. The staining of CCG in semithin sections was amplified after photochemical silver reaction using silver acetate as a silver ion donor and examined under bright-field and epi-illumination microscopy. CCG adjusted to various pH levels was tested on various rat tissues whose histochemical characteristics with regard to acidic glycoconjugates are well known. At pH 2.5 CCG labelled tissues containing sialylated and sulphated acidic glycoconjugates such as the apical cell surface, mucous cells in the distal and proximal colon, and acinar cells of the sublingual gland. In contrast, CCG at pH 1.0 labelled tissues containing sulphated acidic glycoconjugates such as mucous cells in the upper crypt of the proximal colon and mucous cells in the whole crypt of the distal colon. This specificity of CCG was verified by the alteration of CCG staining following several types of cytochemical pretreatment. These results were further confirmed by electron microscopy. CCG staining is thus a useful postembedding procedure for the characterization of acidic glycoconjugates at both the light- and electron-microscopic levels.     

Microbial-host interactions specifically control the glycosylation pattern in intestinal mouse mucosa

The glycosylation of the intestinal cell layer is thought to control several key functions of the gut such as vectorial transports, defence against microbial agents or immunological processes. It has been assumed that the gut microflora may modulate the glycosylation pattern of the intestinal cell layer. However, there is no direct evidence for this regulatory process. The first goal of this work was to establish the germ-free mice intestinal glycosylation baseline using a histochemical approach and a panel of ten lectins with defined glycan specificities to tissue sections prepared from various cellular compartments of the small and large intestine. Using this baseline, we have studied the contribution of the gut microflora on the carbohydrate composition of glycoconjugates of intestinal cells by comparing the germ-free and conventional mice glycosylation patterns. Analysis of the germ-free mice intestinal glycosylation baseline revealed that the expression of glycans depends on the proximodistal gradient (small to large intestine) and on the cell lineage (absorptive, goblet, crypt, and Paneth cells), indicating that mice are able to create and maintain a strict topological and cell lineage-specific regulation of glycosyltransferase expression. By comparing germ-free and conventional mice, we find that the gut microflora specifically modulates the gut glycosylation pattern, quantitatively as well as qualitatively by changing the cellular and subcellular distribution of glycans. This is the first report in mice to directly demonstrate the critical contribution of microflora to intestinal glycosylation, a key characteristic of the gut.     

Peroxidase Localization of Lectin Binding Sites on Plasma Membrane of the Surface Epidermis in the Rusty Blenny,Blennius sanguinolentus (Pallas, 1811)

Abstract Various horseradish peroxidase-conjugated lectins have been used for the ultrastructural localization of carbohydrate moieties of glycoconjugates on plasma membranes of the surface cells of Blennius sanguinolentus epidermis. Concanavalia ensiformis (Con A), Arachis hypogaea (PNA), Pisum sativum (PSA) and Ulex europaeus (UEA I) lectins bind only to the outermost plasma membranes, the glycocalyx and the intercellular spaces of the surface cells. Other lectins applied, such as Triticum vulgare (WGA), Glycine max (SBA) and Griffonia simplicifolia (GS I), presenting GlcNAc and GaINAc specificity, reacted with the plasma membranes of basolateral domains and gave an attenuated reaction with the outermost plasma membranes. The results suggest that regional differences exist in the distribution patterns of GlcNAc and GalNAc-terminating glycoconjugates. The possible implication of the polarized expression of these glycoconjugates in ion transport is discussed.     

Some lectin binding properties of the tongue of the mole rat,Nannospalax xanthodon

We investigated carbohydrate residues on the epithelial surface, in the epithelial cells and in gland cells of the tongue of the mole rat using histochemical methods. We used horseradish peroxidase-conjugated lectins from Helix pomatia (HPA), Arachishypogaea (PNA), Ulexeuropaeus (UEA I), Canavaliaensiformis (Con A). The most intense reactivity was observed in the keratin layer with HPA, UEA I and Con A, and in the epithelial cells with UEA I and Con A. In the glands, we found strong reactivity in serous cells with HPA and Con A, and in mucous cells with HPA and UEA I. PNA did not bind to epithelial or gland cells. Consequently, GlcNAc, fucose and α-D-mannose terminal glycoconjugates are distributed widely; GalNAc terminal glycoconjugates appeared in small amounts.     

Immunolocalization of blood group A gene specified alpha 1,3N-acetylgalactosaminyltransferase and blood group A substance in the trans-tubular network of the Golgi apparatus and mucus of intestinal goblet cells

The subcellular distribution of blood group A gene specified alpha 1,3N-acetylgalactosaminyltransferase and its product was studied in human intestinal goblet cells by immunoelectron microscopy. The O-glycosylation step yielding blood group A-active glycoconjugates occurred in the trans region of the Golgi apparatus as indicated by the presence of immunolabel for both antigens. In the Golgi apparatus, immunoreactive alpha 1,3N-acetylgalactosaminyltransferase was detectable in trans cisternae and in the trans-tubular network which was found to be continuous with the cisternal stack and exhibited acid phosphatase activity. This demonstrates that in intestinal goblet cells (i) the trans-tubular network does not constitute a compartment distinct from trans cisternae, and (ii) structures corresponding to GERL are structurally and functionally part of the Golgi apparatus. In addition to immunolabel for transferase at the inner surface of the cisternal membranes, luminally located immunolabel indicating the presence of free, not membrane-associated transferase became first detectable in the trans-tubular network and early forming mucus droplets contained therein. Further, the content of mature mucus droplets as well as the extracellular mucus layer were labeled. Absence of immunolabel in blood group 0 subjects lacking the blood group A gene specified transferase and the apparent non-reactivity of the antibodies with carbohydrate epitopes indicates that free alpha 1,3N-acetylgalactosaminyltransferase is present in mucus droplets and becomes secreted by intestinal goblet cells.     

Enzymatic large-scale synthesis of MUC6-Tn glycoconjugates for antitumor vaccination

In cancer, mucins are aberrantly O-glycosylated, and consequently, they express tumor-associated antigens such as the Tn determinant (alpha-GalNAc-O-Ser/Thr). As compared with normal tissues, they also exhibit a different pattern of expression. In particular, MUC6, which is normally expressed only in gastric tissues, has been detected in intestinal, pulmonary, colorectal, and breast carcinomas. Recently, we have shown that the MCF7 breast cancer cell line expresses MUC6-Tn glycoproteins in vivo. Cancer-associated mucins show antigenic differences from normal mucins, and as such, they may be used as potential targets for immunotherapy. To develop anticancer vaccines based on the Tn antigen, we prepared several MUC6-Tn glycoconjugates. To this end, we performed the GalNAc enzymatic transfer to two recombinant MUC6 proteins expressed in Escherichia coli, using UDP-N-acetylgalactosamine: polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts), which catalyze in vivo the Tn antigen synthesis. We used either a mixture of ppGalNAc-Ts from MCF7 breast cancer cell extracts or a recombinant ppGalNAc-T1. In both cases, we achieved the synthesis of MUC6-Tn glycoconjugates at a semi-preparative scale (mg amounts). These glycoproteins displayed a high level of Tn antigens, although the overall density depends on both enzyme source and protein acceptor. These MUC6-Tn glycoconjugates were recognized by two anti-Tn monoclonal antibodies that are specific to human cancer cells. Moreover, the MUC6-Tn glycoconjugate glycosylated using MCF7 extracts as the ppGalNAc-T source was able to induce immunoglobulin G (IgG) antibodies that recognized a human tumor cell line. In conclusion, the large-scaled production of MUC6 with tumor-relevant glycoforms holds considerable promise for developing effective anticancer vaccines, and further studies of their immunological properties are warranted.     

Histochemical study of glycoconjugates in the epididymis of the hamster (Mesocricetus auratus)

Summary The glycoconjugates of hamster epididymis were investigated with conventional and lectin histochemistry. A zone of the caput epididymis, with particular histochemical characteristics, has been differentiated. β-Elimination in combination with lectins was used to establish the presence and distribution of N- and O-linked glycoconjugates. The epithelium, spermatozoa and the intertubular matrix were rich in glycoconjugates. The Golgi apparatus and stereocilia of the principal cells were intensely positive with HPA, PNA and SBA lectins. β-limination indicated that these cells contained abundant O-linked glycoconjugates. Apical and clear cells presented a common lectin affinity; their reactivities towards WGA and UEA-I were very positive. These cells probably contain abundant N-glycoconjugates. The spermatozoa were stained by periodic acid-Schiff (PAS) and by all the lectins (especially in the acrosome), except by those with an affinity for α-l-fucosyl residues; the most intense reaction was found with HPA, WGA, PNA and SBA. Changes in the sperm lectin binding along the ductus were observed: sperm flagellum abruptly acquired WGA and PNA labelling from the posterior caput, and HPA reactivity was negative only in the zone between the caput and the corpus.     

Accessibility of glycolipid and oligosaccharide epitopes on rabbit villus and follicle-associated epithelium

The initial step in many mucosal infections is pathogen attachment to glycoconjugates on the apical surfaces of intestinal epithelial cells. We examined the ability of virus-sized (120-nm) and bacterium-sized (1-microm) particles to adhere to specific glycolipids and protein-linked oligosaccharides on the apical surfaces of rabbit Peyer's patch villus enterocytes, follicle-associated enterocytes, and M cells. Particles coated with the B subunit of cholera toxin, which binds the ubiquitous glycolipid GM1, were unable to adhere to enterocytes or M cells. This confirms that both the filamentous brush border glycocalyx on enterocytes and the thin glycoprotein coat on M cells can function as size-selective barriers. Oligosaccharides containing terminal beta(1,4)-linked galactose were accessible to soluble lectin Ricinus communis type I on all epithelial cells but were not accessible to lectin immobilized on beads. Oligosaccharides containing alpha(2, 3)-linked sialic acid were recognized on all epithelial cells by soluble Maackia amurensis lectin II (Mal II). Mal II coated 120-nm (but not 1-microm) particles adhered to follicle-associated enterocytes and M cells but not to villus enterocytes. The differences in receptor availability observed may explain in part the selective attachment of viruses and bacteria to specific cell types in the intestinal mucosa.     

Histochemical differentiation of glycoconjugates occurring in the tilapine intestine

The glycoconjugates secreted by the anterior and posterior intestinal segments of Tilapia spp. were characterized by means of both conventional histochemical procedures (PAS, AB, AB-PAS, LID, HID) and a battery of 12 horseradish peroxidase labelled lectins. Some sections were treated with glycolytic enzymes and KOH before conventional and lectin stainings. The large majority of the mucopolysaccharides secreted by the goblet cells of the anterior segment are carboxylated while only a few carry sulphate groups. The mucopolysaccharides in the anterior intestine contained chondroitin, heparin and chondroitinsulphates which can provide protection for intestinal mucosae. DBA lectin staining demonstrated the presence of some endocrine cells in the anterior segment.     

Detection and mapping of endogenous receptors for carrier-immobilized constituents of glycoconjugates (lectins) by labelled (neo)glycoproteins and by affinity chromatography in human adult mesencephalon, pons, medulla oblongata and cerebellum

Different carrier-immobilized carbohydrate moieties were employed as tools to detect respective binding sites glycohistochemically and glycobiochemically. Besides ascertaining their presence the pattern of endogenous sugar receptors (lectins) in different regions of the human central nervous system was mapped to reveal any non-uniform expression. A strong and specific staining with biotinylated neoglycoproteins, exposing different sugar moieties as ligands, indicated the presence of sugar receptors in the nuclei, neuronal pathways and accessory structures such as ependyma cells, plexus chorioideus, intra- and extracerebral vessels and leptomeninges localized in the mesencephalon, in the pons, in the medulla oblongata and in the cerebellum. Significant differences were seen for various neuroanatomical regions like nerve cells in the basal and central regions of the nuclei pontis in the glycohistochemically detected level of expression of endogenous sugar receptors (lectins). The used approach with carbohydrate constituents of cellular glycoconjugates as ligands in search of specific receptors complemented studies on the localization of glycoconjugates with sugar-specific tools like plant lectins. Exemplary glycobiochemical investigations on the medulla oblongata and cerebellum were performed to investigate the molecular nature of sugar receptors detected glycohistochemically. Despite notable overall similarities, carbohydrate-binding proteins of differing molecular weight can be isolated from these two regions of the central nervous system, namely in the case of receptors with specificity to beta-galactoside termini, to N-acetyl-D-galactosamine and N-acetyl-D-glucosamine and to D-xylose. These combined glycohistochemical and glycobiochemical results serve as a guideline for exploring the physiological relevance of the detected regional differences.     

Lectin-modified trifunctional nanobiosensors for mapping cell surface glycoconjugates

Nanomaterial-based nanobiosensors (nanobiodevices or nanobioprobes) are increasingly emphasized. Here, quantum dots and gamma-Fe(2)O(3) magnetic nanoparticles were co-embedded into single swelling poly(styrene/acrylamide) copolymer nanospheres to fabricate fluorescent-magnetic bifunctional nanospheres. Subsequently, fluorescent-magnetic-biotargeting trifunctional nanobiosensors (TFNS) modified with wheat germ agglutinin (WGA), peanut agglutinin (PNA) or Dolichos biflorus agglutinin (DBA) were conveniently produced so as to bind with A549 cells which are surface-expressed with N-acetylglucosamine, d-galactosamine and N-acetylgalactosamine residues. The values of WGA, PNA and DBA on each nanobiosensor were calculated to be 40, 14 and 60, respectively. These three kinds of lectin-modified trifunctional nanobiosensors (lectin-TFNS) can be used for qualitative and quantitative analysis of the glycoconjugates on A549 cell surface. The fluorescence intensity of WGA-modified nanobiosensors related to N-acetylglucosamine on A549 cell surface was much higher than that of PNA-modified nanobiosensors corresponding to d-galactosamine and that of N-acetylgalactosamine-related DBA-modified nanobiosensors, which is consistent with the results detected by flow cytometry. Lectin-modified trifunctional nanobiosensors not only can quantify the different glycoconjugates on A549 cell surface, but also can recognize and isolate A549 cells. 0.5mg of WGA-modified fluorescent-magnetic trifunctional nanobiosensors could capture 7.0 x 10(4) A549 cells. Therefore, the lectin-modified trifunctional nanobiosensors may be applied in mapping the glycoconjugates on cell surfaces and for recognition and isolation of targeted cells.     

A lectin histochemical study of the oesophagus of shi drum

The saccharide composition of surface and secretion glycoconjugates in the oesophagus of Umbrina cirrosa was examined by means of lectin histochemistry. Mucous cells showed the presence of N‐acetylgalactosamine, N‐acetylglucosamine and sialic acid linked to the dimer galactosyl(β1→3) N‐acetylgalactosamine. Columnar epithelial cells had a positive reaction with almost all the lectins employed, located in the supranuclear region and in the cell coat. The presence of abundant and various glycoconjugates in the secretions of shi drum oesophagus was correlated to the absence of salivary glands in fishes in general.